Algae
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{{for|the programming language|algae (programming language)}}
{{for|the town in Kyrgyzstan|Alga, Kyrgyzstan}}
[[Image:Laurencia.jpg|thumb|right|240px|''[[Laurencia]]'', a marine [[red alga]] from Hawaii.]]
'''Algae''' (''sing''. alga) are a large and diverse group of simple, typically autotrophic organisms, ranging from [[unicellular]] to [[multicellular]] forms. The largest and most complex marine forms are called [[seaweed]]s. They are [[photosynthesis|photosynthetic]], like plants, and "simple" because they lack the many distinct organs found in [[land plants]]. Though the [[Prokaryote|prokaryotic]] ''[[cyanobacteria]]'' (commonly referred to as [[blue-green algae]]) were traditionally included as "algae" in older textbooks, many modern sources regard this as outdated<ref name="IntroBot">Nabors, Murray W., 2004. ''Introduction to Botany.'' Pearson Education, Inc., San Francisco, CA.</ref><ref>The American Heritage Dictionary of the English Language, Fourth Edition, 2000. Algae: [http://www.thefreedictionary.com/algae].</ref> and restrict the term ''algae'' to [[Eukaryote|eukaryotic]] organisms.<ref name="Allaby 92">'''Allaby, M''' ed. 1992. ''The Concise Dictionary of Botany.'' Oxford University Press, Oxford</ref> All true algae therefore have a nucleus enclosed within a membrane and [[chloroplast]]s bound in one or more membranes.<ref name="IntroBot"><ref name="Round 81">'''Round, F.E.''' 1981. ''The Ecology of Algae.'' Cambridge University Press, London. ISBN 0 521 22583 3</ref> Algae constitute a [[paraphyletic]] and [[polyphyletic]] group,<ref name="IntroBot"/> as they do not all descend from a common algal ancestor, although their chloroplasts seem to have a single origin.<ref name="keeling">{{cite journal | title = Diversity and evolutionary history of plastids and their hosts | author = Patrick J. Keeling | url = http://www.amjbot.org/cgi/content/full/91/10/1481 | journal = American Journal of Botany | year = 2004 | volume = 91 | pages = 1481–1493 | doi = 10.3732/ajb.91.10.1481}}</ref>
Algae lack the various structures that characterize land plants, such as phyllids and rhizoids in nonvascular plants, or [[leaf|leaves]], [[root]]s, and other [[Organ (anatomy)|organs]] that are found in [[tracheophytes]]. They are distinguished from [[protozoa]] in that they are photosynthetic. Many are [[autotrophic|photoautotrophic]], although some groups contain members that are [[mixotrophic]], deriving energy both from photosynthesis and uptake of organic carbon either by [[osmotrophy]], [[myzocytosis|myzotrophy]], or [[phagocytosis|phagotrophy]]. Some unicellular [[species]] rely entirely on external energy sources and have limited or no photosynthetic apparatus.
All algae have photosynthetic machinery ultimately derived from the [[cyanobacteria]], and so produce [[oxygen]] as a by-product of photosynthesis, unlike other photosynthetic bacteria such as [[Purple sulfur bacteria|purple]] and [[green sulfur bacteria]].
==Ecology==
Algae are most prominent in bodies of water but are also common in terrestrial environments. However, terrestrial algae are usually rather inconspicuous and far more common in moist, [[tropical]] regions than dry ones, because algae lack [[vascular tissue]]s and other adaptations to live on land. Algae are also found in other situations, such as [[Watermelon snow|on snow]] and on exposed rocks in [[symbiosis]] with a fungus as [[lichen]].
The various sorts of algae play significant roles in aquatic ecology. Microscopic forms that live suspended in the water column ([[phytoplankton]]) provide the food base for most marine [[food chain]]s. In very high densities (so-called [[algal bloom]]s) these algae may discolor the water and outcompete, poison, or asphyxiate other life forms. Seaweeds grow mostly in shallow marine waters, however some have been recorded to a depth of 300 m.<ref name="Round 81"/>Some are used as human food or harvested for useful substances such as [[agar]], [[carrageenan]], or fertilizer.
==Study of algae==
[[Image:AlgaeTree.png|thumb|240px|right|The lineage of algae according to Thomas Cavallier-Smith. The exact number and placement of endosymbiotic events is not yet clear, so this diagram can be taken only as a general guide.<ref name="keeling"/><ref name="parfrey"/> Endosymbiotic events are noted by dotted lines.]]
The study of marine and freshwater algae is called [[phycology]] or algology.
The US Algal Collection is represented by almost 300,000 accessioned and inventoried herbarium specimens.<ref>http://www.nmnh.si.edu/botany/projects/algae/herbarium.htm</ref>
==Classification==
While ''[[Cyanobacteria]]'' have been traditionally included among the algae, referred to as the Cyanophytes or blue-green algae, recent works on algae usually exclude them due to large differences such as the lack of membrane-bound organelles, the presence of a single circular [[chromosome]], the presence of [[peptidoglycan]] in the cell walls, and ribosomes different in size and content from eukaryotes <ref name=BioRaven>''Biology'' 8th ed. Losos, Jonathan B., Mason, Kenneth A., Singer, Susan R., McGraw-Hill. 2007.</ref><ref>[http://www.jochemnet.de/fiu/bot4404/BOT4404_12.html FIU BOT4404 Lecture Notes<!-- Bot generated title -->]</ref>. Rather than in chloroplasts, they conduct photosynthesis on specialized infolded cytoplasmic membranes called [[thylakoid membranes]]. Therefore, they differ significantly from the algae despite occupying similar ecological niches.
By modern definitions algae are [[eukaryotes]] and conduct photosynthesis within membrane-bound organelles called [[chloroplasts]]. Chloroplasts contain circular [[DNA]] and are similar in structure to cyanobacteria, presumably representing reduced cyanobacterial [[endosymbiotic theory|endosymbionts]]. The exact nature of the chloroplasts is different among the different lines of algae, reflecting different endosymbiotic events. The table below lists the three major groups of algae and their lineage relationship is shown in the figure on the left. Note many of these groups contain some members that are no longer photosynthetic. Some retain plastids, but not chloroplasts, while others have lost them entirely.
{| class="wikitable"
|-
! Supergroup affiliation !! Members !! [[Endosymbiont]] !! Summary
|-
|[[Primoplantae]]/<br>[[Archaeplastida]]
|
* [[Chlorophyta]]
* [[Rhodophyta]]
* [[Glaucophyta]]
|Cyanobacterium
|These algae have ''primary'' chloroplasts, i.e. the chloroplasts are surrounded by ''two membranes'' and probably developed through a single endosymbiotic event. The chloroplasts of red algae have chlorophylls ''a'' and ''d'' (often), and [[phycobilin]]s, while those of the green alga have chloroplasts with chlorophyll ''a'' and ''b''. Higher plants are pigmented similarly to green algae and probably developed from them, and thus Chlorophyta is a sister [[taxon]] to the plants; sometimes they are grouped as [[Viridiplantae]].
|-
| [[Excavata]] and [[Rhizaria]]
|
* [[Chlorarachniophytes]]
* [[Euglenids]]
|Green alga
|
These groups have green chloroplasts containing chlorophylls ''a'' and ''b'' <ref name="BioRaven"/>. Their chloroplasts are surrounded by ''four and three membranes'', respectively, and were probably retained from an ingested green alga.
'''Chlorarachniophytes''', which belong to the phylum [[Cercozoa]], contain a small [[nucleomorph]], which is a [[relict]] of the alga's [[cell nucleus|nucleus]].
'''Euglenids''', which belong to the phylum [[Euglenozoa]], live primarily in freshwater and have chloroplasts with only three membranes. It has been suggested that the endosymbiotic green algae were acquired through [[myzocytosis]] rather than [[phagocytosis]].
|-
|[[Chromista]] and [[Alveolata]]
|
* [[Heterokonts]]
* [[Haptophyta]]
* [[Cryptomonad]]s
* [[Dinoflagellates]]
|Red alga
|
These groups have chloroplasts containing chlorophylls ''a'' and ''c'', and phycobilins. The latter chlorophyll type is not known from any prokaryotes or primary chloroplasts, but genetic similarities with the red algae suggest a relationship there.
In the first three of these groups ('''Chromista'''), the chloroplast has four membranes, retaining a nucleomorph in cryptomonads, and they likely share a common pigmented ancestor, although other evidence casts doubt on whether the [[Heterokonts]], [[Haptophyta]], and [[Cryptomonad]]s are in fact more closely related to each other than other groups.<ref>{{cite journal | author = Burki F, Shalchian-Tabrizi K, Minge M, Skjæveland Å, Nikolaev SI, et al. | year = 2007 | title = Phylogenomics Reshuffles the Eukaryotic Supergroups | journal = PLoS ONE | volume = 2 | issue = 8: e790 | doi = 10.1371/journal.pone.0000790 | pages = e790}}</ref><ref name="parfrey">{{cite journal | url = http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1713255 | title = Evaluating Support for the Current Classification of Eukaryotic Diversity | author = Laura Wegener Parfrey, Erika Barbero, Elyse Lasser, Micah Dunthorn, Debashish Bhattacharya, David J Patterson, and Laura A Katz | doi = 10.1371/journal.pgen.0020220 | journal = PLoS Genet. | date = 2006 December | volume = 2 | issue = 12 | pages = e220 | pmid = 17194223 }}</ref>
The typical '''dinoflagellate''' chloroplast has three membranes, but there is considerable diversity in chloroplasts among the group, and it appears there were a number of endosymbiotic events here.<ref name="keeling"/> The [[Apicomplexa]], a group of closely related parasites, also have [[plastid]]s called [[apicoplast]]s. Apicoplasts are not photosynthetic but appear to have a common origin with dinoflagellates chloroplasts.<ref name="keeling"/>
|}
It was [[W.H.Harvey]] (1811 — 1866) who first divided the algae into four divisions based on their pigmentation. This is the first use of a biochemical criterion in plant systematics. Harvey's four divisions were: red algae (Rhodophyta), brown algae (Heteromontophyta), green algae (Chlorophyta) and Diatomaceae (Dixon, 1973 p.232).<ref name="Dixon 73" p.232>'''Dixon, P.S.''' 1973 ''Biology of the Rhodophyta.'' Oliver & Boyd, Edinburgh. ISBN 0 05 002485 X</ref>
== Forms of algae ==
Most of the simpler algae are [[unicellular]] [[flagellate]]s or [[amoeboid]]s, but colonial and non-motile forms have developed independently among several of the groups. Some of the more common organizational levels, more than one of which may occur in the [[biological life cycle|life cycle]] of a species, are
* ''Colonial'': small, regular groups of motile cells
* ''Capsoid'': individual non-motile cells embedded in [[mucilage]]
* ''Coccoid'': individual non-motile cells with cell walls
* ''Palmelloid'': non-motile cells embedded in mucilage
* ''Filamentous'': a string of non-motile cells connected together, sometimes branching
* ''Parenchymatous'': cells forming a [[thallus (tissue)|thallus]] with partial differentiation of tissues
In three lines even higher levels of organization have been reached, with full tissue differentiation. These are the [[brown algae]] <ref>http://www.ucmp.berkeley.edu/chromista/phaeophyta.html</ref>—some of which may reach 50 m in length ([[kelp]]s)<ref name="Thomas 02">'''Thomas, D.N.''' 2002 ''Seaweeds.'' The Natural History Museum, London. ISBN 0 565 09175 1</ref>—the [[red alga]]e <ref>http://www.ucmp.berkeley.edu/protista/rhodophyta.html</ref>, and the [[green alga]]e <ref>http://www.ucmp.berkeley.edu/greenalgae/greenalgae.html</ref>. The most complex forms are found among the green algae (see [[Charales]] and [[Charophyta]]), in a lineage that eventually led to the higher [[land plants]]. The point where these non-algal plants begin and algae stop is usually taken to be the presence of reproductive organs with protective cell layers, a characteristic not found in the other alga groups.
The first plants on earth evolved from shallow freshwater algae much like ''Chara'' some 400 million years ago. These probably had an isomorphic alternation of generations and were probably heterotrichous. Fossils of isolated land plant spores suggest land plants may have been around as long as 475 million years ago.{{Fact|date=December 2007}}
== Algae and symbioses==
Some species of algae form [[symbiosis|symbiotic relationships]] with other organisms. In these [[symbioses]], the algae supply photosynthates (organic substances) to the host organism providing protection to the algal cells. The host organism derives some or all of its energy requirements from the algae. Examples include
* ''[[lichen]]s'': a fungus is the host, usually with a green alga or a cyanobacterium as its symbiont. Both fungal and algal species found in lichens are capable of living independently, although habitat requirements may be greatly different from those of the lichen pair.
* ''[[coral]]s'': algae known as [[zooxanthella]]e are symbionts with [[coral]]s. Notable amongst these is the dinoflagellate ''Symbiodinium'', found in many hard corals. The loss of ''Symbiodinium'', or other zooxanthellae, from the host is known as [[coral bleaching]].
* ''[[sea sponge|sponge]]s'': green algae live close to the surface of some sponges, for example, breadcrumb sponge (''[[Halichondria panicea]]''). The alga is thus protected from predators; the sponge is provided with oxygen and sugars which can account for 50 to 80% of sponge growth in some species.<ref>http://uwsp.edu/cnr/UWEXlakes/laketides/vol26-4/vol26-4.pdf</ref>
==Life-cycle==
[[Rhodophyta]], [[Chlorophyta]] and [[Heterokontophyta]], the three main algal [[phylum|Phyla]], have life-cycles which show tremendous variation with considerable complexity. In general there is an asexual phase where the seaweed's cells are [[diploid]], a sexual phase where the cells are [[haploid]] followed by fusion of the male and female [[gametes]]. Asexual reproduction is advantageous in that it permits efficient population increases, but less variation is possible. Sexual reproduction allows more variation but is more costly because of the waste of gametes that fail to mate, among other things. Often there is no strict alternation between the sporophyte and gametophyte phases and also because there is often an asexual phase, which could include the fragmentation of the thallus.<ref name="Thomas 02">'''Thomas, D.N.''' 2002 ''Seaweeds.'' The Natural History Museum, London. ISBN 0 565 09175 1</ref><ref name="Lobban and Harrison 94">'''Lobban, C.S. and Harrison, P.J.''' 1997. ''Seaweed Ecology and Physiology.'' Cambridge Uiversity Press. ISBN 0-521-40897-00</ref><ref>http://scitec.uwichill.edu.bb/bcs/bl14apl/algae2.htm</ref>
===See also===
[[Conceptacle]]
==Numbers and distribution==
In the British Isles the UK Biodiversity Steering Group Report estimated there to be 20,000 algal species in the UK, freshwater and marine, about 650 of these are seaweeds. Another checklist of freshwater algae reported only about 5000 species. It seems therefore that the 20,000 is an overestimate or an error (John, 2002 p.1).<ref name="John 02">'''John, D.M., Whitton, B.A. and Brook, A.J.''' 2002. ''The Freshwater Algae Flora of the British Isles.'' Cambridge University Press, Cambridge. ISBN 0 521 77051 3</ref>
The Smithsonian collection of algae has over 300,000 specimens. <ref name="US algal">[http://www.nmnh.si.edu/botany/projects/algae/ Algae Research/ Department of Botany, National Museum of Natural History, Smithsonian Institution<!-- Bot generated title -->]</ref>
World-wide it is thought that there are over 5,000 species of red algae, 1,500 — 2,000 of brown algae and 8,000 of green algae. In Australia it is estimated that there are over 1,300 species of red algae, 350 species of brown algae and approximately 2,000 species of green algae totalling 3,650 species of algae in Australia.<ref name="Huisman 00">'''Huisman, J.M.''' 2000. ''Marine Plants of Australia.'' University of Western Australian Press, Australian Biological Resources Study. ISBN 1 876268 33 6</ref>
Around 400 species appear to be an average figure for the coastline of South [[Africa]]n west coast.<ref name="Stegenga 97">'''Stegenga, H., Bolton, J.J. and Anderson, R.J.''' 1997. ''In'' Hall, A.V. (Ed.) '' Seaweeds of the South African West coast.'' Bolus Herbarim No. 18. ISBN 0-7992-1793-X</ref>
669 marine species have been described from California (U.S.A.).<ref name="Abbott and Hollenberg 76">'''Abbott, I.A. and Hollenberg, G.J.''' 1976. ''Marine Algae of [[California]].'' Stanford University Press, California. ISBN 0-8047-0867-3</ref>
642 entities are listed in the check-list of Britain and Ireland (Hardy and Guiry, 2006).<ref name="Hardy nad Guiry 06">'''Hardy, F.G. and Guiry, M.D. ''' 2006. ''A Check-list and Atlas of the Seaweeds of Britain and Ireland.'' Britiah Phycological Society, London. ISBN 3-906166-35-X</ref>
==Distribution==
No publication has been found which attempts to discuss the general distribution of algae in the seas world-wide. However, notes and comments have been made by some authors.
The floristic discontinuities may appear to determined by geographical features such as [[Antarctica]], long distances of ocean or general land masses. However, the distances between Norway, the Faroes and Iceland do not show great changes in distribution.<ref name="Round 81"/>
There has been dispersal in some species by ships, water currents and the like; further, some algae can quickly become entangled and make drifting mats.<ref name="Kain and Norton">'''Kain, J.M. and Noron, T.A.''' 1990. Marine ecology. p.397. ''in'' Cole, K.M. and Sheath, R.G. 1990. ''Biology of Red Algae.'' Cambridge University Press. ISBN 0 521 343101 1</ref> Two red species have been introduced from the [[Pacific]] to [[Europe]] and the [[Mediterranean]]: ''Bonnemaisonia hamifera'' Hariot and ''Asparagopsis armata'' Harvey,<ref name="Guiry 91"> '''Guiry, M.D. and Garbary, D.J.'''. A Geographical and Taxonomic Guide to European Seaweeds of Economic Importance. ''in'' ''Seaweeds Resources In Europe: Uses and Potential.'' ed. Guiry, M.D. and Blunden, G. 1991. John Wiley and Sons. ISBN 0 471 92947 6</ref> ''A. armata'' is a native of [[Australia]].<ref name="Round 81">[http://www.algaebase.org/search/species/detail/?species_id=6&-session=abv4:51909EC30ef17250FFlvO11DCEF5 www.algaebase.org]</ref>''[[Colpomenia peregrina]]'' is a native of the Pacific but has also invaded Europe.
===Britain and Ireland===
*'''Hardy, F.G.''' and '''Guiry, M.D.''' 2006. ''A Check-list and Atlas of the Seaweeds of Britain and Ireland.'' British Phycological Society, London. ISBN 3 906166 35 X
*'''Cullinane, J.P.''' 1973. ''Phycology of the South Coast of Ireland.'' The Cork University Press, University College Cork.
===Northumberland and Durham (England)===
*'''Hardy, F.G.''' and '''Aspinall, R.J.''' 1988. ''An Atlas of the Seaweeds of Northumberland and Durham.'' Northumberland Biological Records Centre. The Hancock Museum. The University Newcastle upon Tyne. Special publication: 3. ISBN 0 9509680 5 6
===Northern Ireland===
*'''Morton, O.''' 1994. ''Marine Algae of Northern Ireland.'' Ulster Museum, Belfast. ISBN 0 900761 28 8
===Republic of Ireland: County Donegal===
*'''Morton, O.''' The marine macroalgae of County Donegal, Ireland. ''Bull. Ir. biogeog. Soc.'' '''27''':3 - 164.
===Isle of Man===
*'''Knight, M.''' and '''Park, M.W.''' 1931. Manx algae. An algal survey of the south end of the Isle of Man. ''L.M.B.C. Mem. Typ. Br. Mar. Pl. '' '''390''': 1 - 155.
===Arctic===
*'''Kjellman, F.R.''' 1883. The algae of the Arctic Sea. ''K. sevenka. VetenskAkad. Handl.'' '''20''': 1 - 350.
===Greenland===
*'''Lund, S.''' 1959. ''The Marine Algae of East Greenland. I. Taxonomical part. ''Meddr. Grønland '''156''': 1 - 247.
===Faroe Islands===
*'''Borgesen, F.''' 1903. Marine Algae, pp.339 - 532. ''In'', Warming, E. (Ed.), ''Botany of the Faröes Based Upon Danish Investigations.'' Part II. Copenhagen. [reprint 1970]
===Atlantic(east coast)/Europe===
*'''Cabioc'h,J., Floc'h,J-Y., Le Toquin, A., Boudouresque, C-F., Meinesz, A.''' and '''Verlaque, M.''' 1992. ''Guide des algues des mers d'Europe.'' Delachaux et Niestlé, Switzerland.
*'''Gayral, P.''' 1958 ''Algues de la Côte Atlantique Marocaine.'' Rabat.
*'''Gayral, P.''' 1966. ''Algues des Côtes Françaises.'' Paris.
===Canary Islands.===
*'''Borgesen,F.''' 1925. Marine algae from the Canary Islands, especially from Tenerife and Gran Canaria. I. Chlorophyceae. ''Biol. Meddr'' '''5''': 1 - 113.
*'''Borgesen,F.''' 1926. Marine algae from the Canary Islands especially from Tenerife and Gran Canaria. II. Phaeophyceae. ''Biol. Meddr'' '''6''': 1 - 112.
*'''Borgesen,F.''' 1927. Marine algae from the Canary Islands. III. Rhodophyceae. Part I, Bangiales and Nemalionales. ''Biol. Meddr'' '''6''': 1 - 97.
*'''Borgesen,F.''' 1929. Marine algae from the Canary Islands. III Rhodophyceae. Part II. Cryptonemiales, Gigartinales and Rhodymeniales. ''Biol. Meddr'' '''8''': 1 - 97.
*'''Borgesen,F.''' 1930. Marine algae from the Canary Islands. III Rhodophyceae. Part II. Cryptonemiales, Gigartinales and Rhodymeniales. ''Biol. Meddr'' '''9''': 1 - 159.
===North America===
*'''Taylor, W.R.''' 1957. ''Marine Algae of the Northeastern Coast of North America.'' University of Michigan Press, Ann Arbor.
*'''Abbott, I.A.''' and '''Hollenberg, G.J.''' 1976. ''Marine Algae of California.'' Stanford University Press, California.
*'''Wehr, J.D.''' and '''Sheath, R.G.''' 2003. ''Freshwater Algae of North America: Ecology and Classification.'' Academic Press, USA.
===South Africa===
*'''Stegenga, H. Bolton, J.J.''' and '''Anderson, R.J. 1997.''' ''Seaweeds of the South African West Coast.'' Bolus Herbarium Number 18, Publication jointly financed by the Fourcade Bequest and the Research Committee of the University of Cape Town and the Foundation for Research Development.
===New Zealand===
*'''Lindauer, V.W., Chapman, V.J.''' and '''Aiken, M.''' 1961. The Marine Algae of New Zealand. Part II. Phaeophyta. ''Nova Hedwigia'' '''3''': 129 - 350.
*'''Chapman, V.J.''' 1969. ''The Marine Algae of New Zealand. Part III issues 1''. Lehre: J.Cramer, 1 - 113.
*'''Chapman, V.J.''' and '''Dromgoole, F.I.''' 1970. ''The Marine Algae of New Zealand. Part III issues 2.'' Lehre: J.Cramer, 115 - 154.
*'''Chapman, V.J.''' and '''Parkinson, P.G.''' 1974 ''The Marine Algae of New Zealand. Part III issues 3.'' Lehre: J.Cramer,155 - 278.
*'''Chapman, V.J.''' 1979 ''The Marine Algae of New Zealand. Part III issues 4.'' Lehre: J.Cramer, 279 - 420.
== Uses of algae ==
[[Image:Seaweed.jpg|right|thumb|[[Seaweed]] is used as a fertilizer]]
===Fertilizer===
For centuries seaweed has been used as a fertilizer; Orwell writing in the 16th century referring to drift weed in South Wales: "This kind of ore they often gather and lay in heaps where it heats and rots, and will have a strong and loathsome smell; when being so rotten they cast it on the land, as they do their muck, and thereof springeth good corn, especially barley" and "After spring tides or great rigs of the sea, they fetch it in sacks on horse brackets, and carry the same three, four, or five miles, and cast it on the lande, which doth very much better the ground for corn and grass" (Chapman p.35).<ref name="Chapman 50">'''Chapman, V.J.''' 1950. ''Seaweeds and their Uses.'' Methuen & Co. Ltd., London</ref>
Algae are used by humans in many ways. They are used as fertilizers, soil conditioners and are a source of livestock feed.<ref name="Thomas 02">'''Thomas, D.N.''' 2002 ''Seaweeds.'' The Natural History Museum, London. ISBN 0 565 09175 1</ref> Because many species are aquatic and microscopic, they are cultured in clear tanks or ponds and either harvested or used to treat effluents pumped through the ponds. [[Algaculture]] on a large scale is an important type of [[aquaculture]] in some places.
[[Maerl]] is commonly used as a soil conditioner, it is dredged from the sea floor and crushed to form a powder.<ref name="Thomas 02"/> It is still harvested around the coasts of [[Brittany]] in [[France]] and off [[Falmouth, Cornwall]] (also extensively in western Ireland) and is a popular fertilizer in these days of organic gardening investigated Falmouth maerl and found that ''L. corallioides'' predominated down to 6 m and ''P. calcareum'' from 6-10 m (Blunden ''et al.'', 1981).<ref name="Blunden 81"> '''Blunden, G., Farnham, W.F. Jephson, N., Barwell, C.J., Fenn, R.H. and Plunkett, B.A.''' 1981 The composition of maerl beds of economic interest in northern Brittany, Cornwall, and Ireland. ''Proceedings of the International Seaweed Symposium.'' '''10''': 651 - 656</ref><ref name="Blunden 97">'''Blunden, G., Campbell, S.A., Smith, J.R., Guiry, M.D., Hession, C.C. and Griffin, R.L.''' 1997. Chemical and physical characterization of calcified red algal deposits known as maërl. ''J. Applied. phycol.'' '''9''': 11 - 17</ref>
Chemical analysis of maerl showed that it contained 32.1% CaCO<sub>3</sub> and 3.1% MgCO<sub>3</sub> (dry weight).
===Energy source===
{{Main|algaculture}}
* Algae can be used to make [[biodiesel]] (see [[algaculture#Biodiesel production|algaculture]]), [[bioethanol]] and [[biobutanol]] and by some estimates can produce vastly superior amounts of [[vegetable oil]], compared to terrestrial crops grown for the same purpose.
* Algae can be grown to produce [[biohydrogen]]. In 1939 a German researcher named [[Hans Gaffron]], while working at the University of Chicago, observed that the algae he was studying, ''[[Chlamydomonas reinhardtii]]'' (a green-alga), would sometimes switch from the production of oxygen to the production of hydrogen.<ref>http://www.wired.com/news/technology/0,1282,54456,00.html</ref> Gaffron never discovered the cause for this change and for many years other scientists failed to repeat his findings. In the late 1990s professor Anastasios Melis, a researcher at the University of California at Berkeley, discovered that if the algae culture medium is deprived of sulfur it will switch from the production of oxygen (normal photosynthesis), to the production of hydrogen. He found that the [[enzyme]] responsible for this reaction is [[hydrogenase]], but that the hydrogenase lost this function in the presence of oxygen. Melis found that depleting the amount of sulfur available to the algae interrupted its internal oxygen flow, allowing the hydrogenase an environment in which it can react, causing the algae to produce hydrogen. <ref>http://www.wired.com/wired/archive/10.04/mustread.html?pg=5</ref> ''Chlamydomonas moeweesi'' is also a good strain for the production of hydrogen. Scientists at the U.S. Department of Energy’s Argonne National Laboratory are currently trying to find a way to take the part of the hydrogenase enzyme that creates the hydrogen gas and introduce it into the photosynthesis process. The result would be a large amount of hydrogen gas, possibly on par with the amount of oxygen created.<ref>[http://newswise.com/articles/view/539260/ Algae Could One Day be Major Hydrogen Fuel Source] Newswise, Retrieved on June 30, 2008.</ref>
* Algae can be grown to produce [[biomass]], which can be burned to produce heat and electricity. <ref>http://pmb.berkeley.edu/newPMB/faculty/melis/melis.shtml</ref>
* Algae can be used in oil production which could replace the petrol and other gas products in the near future.
===Pollution control===
* Algae are used in wastewater treatment facilities, reducing the need for greater amounts of toxic chemicals than are already used.
* Algae can be used to capture [[fertilizers]] in runoff from farms. When subsequently harvested, the enriched algae itself can be used as fertilizer.
* [[Algae Bioreactors]] are used by some powerplants to reduce CO<sub>2</sub> [[emissions]]. <ref>http://www.usatoday.com/tech/science/2006-01-10-algae-powerplants_x.htm</ref> The CO<sub>2</sub> can be pumped into a pond, or some kind of tank, on which the algae feed. Alternatively, the bioreactor can be installed directly on top of a smokestack. This technology has been pioneered by Massachusetts-based GreenFuelTechnologies.<ref>http://www.greenfuelonline.com/</ref>
===Stabilizing substances===
''[[Chondrus crispus]]'', (probably confused with ''[[Mastocarpus stellatus]]'', common name: Irish moss), is also used as "[[carrageen]]". The name carrageenan comes from the Irish Gaelic for ''Chondrus crispus''. It is an excellent stabiliser in milk products - it reacts with the milk protein caesin, other products include: petfoods, toothpaste, ice-creams and lotions etc.<ref name="Stegenga 97"/><ref name="Lewis ''et al'' 88"/> Alginates in creams and lotions are absorbable through the skin.<ref name="Roeck-Holtzhauer 91"> Roeck-Holtzhauer,Y de Uses of Seaweeds in Cosmetics. in '''Guiry, M.D. and Blunden, G.''' 1991. ''Seaweed Resources in Europe; Uses and Potential.'' John Wiley & Sons. ISBN 0 471 92947 6</ref>
===Nutrition===
Seaweeds are an important source of food, especially in Asia; They are excellent sources of many vitamins including: A, [[Thiamine|B1]], [[Riboflavin|B2]], [[Vitamin B6|B6]], [[niacin]] and [[Vitamin C|C]]. They are rich in [[iodine]], [[potassium]], [[iron]], [[magnesium]] and [[calcium]].<ref name="Mondragon 03"> '''Mondragon, J. and Mondragon, J.''' 2003. ''Seaweeds of the Pacific Coast.'' Sea Challengers Publications, Monterey, California. ISBN 0-930118-29-4</ref>
Algae is commercially cultivated as a nutritional supplement. One of the most popular [[microalgal]] species is [[Spirulina (dietary supplement)|Spirulina]] ''(Arthrospira platensis),'' which is a [[Cyanobacteria]] (known as blue-green algae), and has been hailed by some as a superfood.<ref>http://www.siu.edu/~ebl/leaflets/algae.htm</ref> Other algal species cultivated for their nutritional value include; [[Chlorella]] (a green algae), and [[Dunaliella]] (''Dunaliella salina''), which is high in [[beta-carotene]] and is used in vitamin C supplements.
In China at least 70 species of algae are eaten as is the Chinese "vegetable" known as ''[[fat choy (vegetable)|fat choy]]'' (which is actually a [[cyanobacterium]]). Roughly 20 species of algae are used in everyday cooking in Japan.<ref name="Mondragon 03"> '''Mondragon, J. and Mondragon, J.''' 2003. ''Seaweeds of the Pacific Coast.'' Sea Challengers Publications, Monterey. ISBN 0-930118-29-4</ref>
Certain species are edible; the best known, especially in Ireland is ''[[Palmaria palmata]]'' (Linnaeus) O. Kuntze, also known as ''Rhodymenia palmata'' (Linnaeus) Kuntze, common name: [[dulse]]).[http://www.seaveg.co.uk/dulse.html] This is a red alga which is dried and may be bought in the shops in [[Ireland]]. It is eaten raw, fresh or dried, or cooked like spinach. Similarly, ''Durvillaea antarctica'' [http://www.algaebase.org/speciesdetail.lasso?species_id=11752&sk=0&from=results&-session=abv3:51909EC30802716127sVj3EDC9C7] is eaten in Chile, common name: cochayuyo.
<ref>http://www.seaveg.co.uk/dulse.html</ref>
''[[Porphyra]]'' (common name: purple [[laver (seaweed)|laver]]), is also collected and used in a variety of ways (e.g. "laver bread" in the British Isles). In Ireland it is collected and made into a jelly by stewing or boiling. Preparation also involves frying with fat or converting to a pinkish jelly by heating the fronds in a saucepan with a little water and beating with a fork. It is also collected and used by people parts of Asia, specifically China, Korea ([[Gim (Korean food)|gim]]) and Japan ([[nori]]) and along most of the coast from [[California]] to [[British Columbia]]. The Hawaiians and the Maoris of [[New Zealand]] also use it.
One particular use is in "instant" puddings, sauces and creams. ''Ulva lactuca'' (common name: sea lettuce), is used locally in Scotland where it is added to soups or used in salads. ''[[Alaria esculenta]]'' (common name: badderlocks or dabberlocks), is used either fresh or cooked, in [[Greenland]], [[Iceland]], [[Scotland]] and Ireland.
The oil from some algae have high levels of unsaturated fatty acids. [[Arachidonic acid]] (a polyunsaturated fatty acid), is very high in ''[[Parietochloris incisa]]'', (a green alga) where it reaches up to 47% of the triglyceride pool (Bigogno C et al. Phytochemistry 2002, 60, 497). <ref>http://www.spirulinasource.com/earthfoodch8a.html</ref> <ref>http://www.cfsan.fda.gov/~rdb/opa-g137.html</ref>
It is a known fact that fish oil contains the omega-3 fatty acids docosahexaenoic acid, commonly known as DHA and eicosapentaenoic acid, or EPA; but The Martek Biosciences Corporation who discovered the source of DHA to be from algae manufactures DHA from algae, which is where fish get their DHA, explains J. Casey Lippmeier, Martek's senior scientist.
The algae are eaten by smaller marine life such as copepods, "and those are eaten by slightly larger fish," says Lippmeier. The DHA gets passed along the food chain, all the way up to the biggest fish, but the original source is the algae.
You can refer to the following npr.org link for an article on algae and omega-3 fatty acids; http://www.npr.org/templates/story/story.php?storyId=15823852.
===Other uses===
There are also commercial uses of algae as agar.<ref name="Lewis ''et al'' 88">'''Lewis, J.G., Stanley, N.F and Guist, G.G.''' 1988. 9 Commercial production of algal hydrocolloides. ''in'' Lembi, C.A. and Waaland, J.R. (Eds.) ''Algae and Human Affairs.'' Cambridge University Press, Cambridge ISBN 0 521 32115 8</ref>
The natural [[pigment]]s produced by algae can be used as an alternative to chemical [[dyes]] and coloring agents.<ref>http://www.bgu.ac.il/bgn/Microalgae.html</ref> Many of the paper products used today are not recyclable because of the chemical inks that they use, paper recyclers have found that inks made from algae are much easier to break down. There is also much interest in the food industry into replacing the coloring agents that are currently used with coloring derived from algal pigments. Algae can be used to make pharmaceuticals<ref name="Capture and sequestration of CO2From Stationary Combustion Systems by Photosynthesis of Microalgae">Capture and sequestration of CO2From Stationary Combustion Systems by Photosynthesis of Microalgae</ref>Sewage can be treated with algae as well<ref name="Smithsonian">[http://www.nmnh.si.edu/botany/projects/algae/economicuses/industrial.htm Industrial and other uses - Department of Botany - Smithsonian Museum of Natural History]</ref>
Some cosmetics can come from microalgae as well.
In [[Israel]], a species of green algae is grown in water tanks, then exposed to direct sunlight and heat which causes it to become bright red in color. It is then harvested and used as a natural pigment for foods such as Salmon.<ref>http://www.time.com/time/magazine/article/0,9171,1616252,00.html</ref>
===Alginates===
Between 100,000 and 170,000 wet tons of ''[[Macrocystis]]'' are harvested annually in [[California]] for alginate extraction and abalone feed.<ref>http://www.algaebase.org/generadetail.lasso?genus_id=35715&-session=abv3:51909EC307dcf25DFApmi3530315</ref>
<ref>http://www.nmnh.si.edu/botany/projects/algae/economicuses.htm</ref>
===Further references to the uses===
* '''Guiry, M.D. and Blunden, G.''' (Eds) 1991. ''Seaweed Resources in Europe: Uses and Potential''. John Wiley & Sons. ISBN 0-471-92947-6
* '''Mumford, T.F. and Miura, A.''' 1988. 4. ''Porphyra'' as food: cultivation and economics. p.87 — 117. In Lembi, C.A. and Waaland, J.R. (Ed.) ''Algae and Human Affairs''. 1988. Cambridge University Press. ISBN 0 521 32115 8
==Collecting and preserving specimens==
Seaweed specimens can be collected and preserved for research. Such preserved specimens will keep for two or three hundred years. Those of [[Carl von Linné]] (1707 — 1778) are still available for reference, and are used. Specimens may be collected from the shore; those below low tide must be collected by diving or dredging. The whole algal specimen should be collected, that is the [[holdfast]], stipe and lamina. Specimens of algae reproducing will be the more useful for identification and research. When collected the details of the location and site should be noted. They can then be preserved pressed on paper or in a preserving liquid such as alcohol or solution of 5 per cent formalin/seawater. However, formalin is reported to be carcinogenic.<ref name="Huisman 00">'''Huisman, J.M.''' 2000. ''Marine Plants of Australia.'' University of Western Australia Press, Nedlands, Western Australia. ISBN 1 876268 33 6</ref>
==Ecology==
===Biological Exposure Scale===
The ecology of the shores of the British Isles, including a discussion of the different shores from sheltered to exposed along with an exposure scale, is given by Lewis (1964).<ref name="Lewis 64">'''Lewis, J.R.''' 1964. ''The Ecology of Rocky Shores.'' The English Universities Press, London</ref> An exposure scale of five stages is given:- Very Exposed Shores; Exposed Shores; Semi-exposed Shores; Sheltered Shores and Very Sheltered Shores. Factors indicating the differences between these exposure scales are detailed. Very Exposed Shores have a wide ''Verrucaria'' zone entirely above the upper tide level, a ''Porphyra'' zone above the barnacle level and ''Lichina pygmaea'' is locally abundant. The eulittoral zone is dominated by [[barnacles]] and [[limpets]] with a coralline belt in the very low littoral along with other Rhodophyta and ''[[Alaria]]'' in the upper sublittoral. Exposed shores show a ''Verrucaria'' belt mainly above the high tide, with ''Porphyra'' and ''Lichina pygmaea''. The mid shore is dominated by barnacles, limpets and some ''Fucus''. Some Rhodophyta. ''Himanthalia'' and some Rhodophyta such as ''Mastocarpus'' and ''Corallina'' are found in the low littorral with ''Himanthalia'', ''[[Alaria]]'' and ''[[Laminaria]] digitata'' dominant in the upper sublittoral. The semi-exposed shores show a ''Verrucaria'' belt just above high tide with clear ''Pelvetia'' in the upper-littoral and ''Fucus serratus'' in the lower-littoral. Limpets, barnacles and short ''Fucus vesiculosus'' midshore. ''Fucus serratus'' with Rhodophyta, (''Laurencia'', ''[[Mastocarpus stellatus]]'', ''Rhodymenia'' and ''Lomentaria''). ''Laminaria'' and ''Saccorhiza polyschides'' and small algae common in the sublittoral. The sheltered shores show a narrow ''Verrucaria'' zone at high water and a full sequence of fucoids: ''Pelvetia'', ''Fucus spiralis'', ''Fucus vesiculosus'', ''Fucus serratus'', ''Ascophyllum nodosum''. ''Laminaria digitata'' is dominant the upper sublittoral. The very sheltered shores show a very narrow zone of ''Verrucaria'', the dominance of the littoral by a full sequence of the fucoids and ''Ascophyllum'' covering the rocks. ''Laminaria saccharina'', ''Halidrys'', ''Chondrus'' and or ''Furcellaria''.<ref name="Lewis 64"/>
==Common names==
* ''[[Alaria sculenta]]'' Dabberlocks<ref name=Dickson63>'''Dickson,C.I.''' 1963. ''Brtish Seaweeds.'' The Kew Series, Eyre & Spottiswoode</ref>; Edible kelp
* ''[[Ascophyllum nodosum]]'' Knotted wrack<ref name=Dickson63/>
* ''[[Chondrus crispus]]'' Carragheen<ref name=Dickson63/>; Irish moss
* ''[[Chorda filum]]'' Sea lace<ref name=Dickson63/>
* ''[[Colpomena peregrina]]'' Oyster thief<ref name=Dickson63/>
* ''[[Fucus]]'' Wrack<ref name=Dickson63/>
* ''[[Fucus ceranoides]]'' Horned wrack<ref name=Dickson63/>
* ''[[Fucus serratus]]'' Toothwrack<ref name=Dickson63/>
* ''[[Fucus vesiculosus]]'' Bladderwrack<ref name=Dickson63/>
* ''[[Fucus spirals]]'' Spiral wrack<ref name=Dickson63/>
* ''[[Haldrys siliquosa]]'' Sea oak<ref name=Dickson63/>
* ''[[Halurus euisetifolius]]'' Seatail<ref name=Dickson63/>
* ''[[Himanthalia elongata]]'' Sea thong<ref name=Dickson63/>; Thong-weed
* ''[[Laminaria digitata]]'' Tangle<ref name=Dickson63/>; Oarweed
* ''[[Laminaria hyperborea]]'' Curvie<ref name=Dickson63/>
* ''[[Laminaria saccharina]]'' Sea belt<ref name=Dickson63/>; Sugar Kelp; Sugarwrack
* ''[[Laurencia pinnatifida]]'' Pepper dulse<ref name=Dickson63/>
* ''[[Padin pavonia]]'' Peacocks<ref name=Dickson63/>
* ''[[Palmaria palmata]]'' Dulse<ref name=Dickson63/>
* ''[[Pelvetia canaliculata]]'' Channelled wrack<ref name=Dickson63/>
* ''[[Plocamium vulgare]]'' Cockscomb<ref name=Dickson63/>
* ''[[Polyides caprinus]]'' Goat tang<ref name=Dickson63/>
* ''[[Polysiphonia elongata]]'' Lobster horns<ref name=Dickson63/>
* ''[[Porphyra umbilicalis]]'' Purple laver<ref name=Dickson63/>; Laver
* ''[[Saccorhiza polyschides]]'' Furbelows<ref name=Dickson63/>
* ''[[Ulva lactuca]]'' Sea lettuce<ref name=Dickson63/>
==Examples==
*''[[Atractophora hypnoides]]'' P.L.Crouan and H.M.Crouan ([[red algae]])
*''[[Ascophyllum nodosum]]''
*''[[Charales]]'' ([[green algae]])
*''[[Codium]]''
*''[[Fucus]]''
*''[[Ulva lactuca]]''
*''[[Laminaria]]''
*''[[Lemanea]]''
*''[[Macrocystis]]''
*''[[Mastocarpus stellatus]]''
*''[[Pelvetia canaliculata]]''
*''[[Palmaria palmata]]''
*''[[Porphyra]]''
*''[[Postelsia palmaeformis]]''
==See also==
* [[Algaculture]]
* [[Biological hydrogen production (Algae)]]
* [[Brown Algae]]
* [[Chlorophyta]]
* [[Coccolithophore]]
* [[Conceptacle]]
* [[Coralline algae]]
* [[Cyanobacteria]]
* [[Diatom]]
* [[Golden Algae]]
* [[Green Algae]]
* [[Hydrology transport model]]
* [[List of publications in biology#Phycology|Important publications in phycology]]
* [[Kelp]]
* [[Laminaria|''Laminaria'']]
* [[Nori]]
* [[Red Algae]]
* [[Yellow-Green Algae]]
* [[Marimo]]
* [[History of phycology]]
==References==
===Cited references===
{{reflist}}
===Identification===
* Abbott, I.A. and Hollenberg, G.J. 1976. ''Marine Algae of California.'' Stanford University Press, California. ISBN 0-8047-0867-3
* Brodie, J.A. and Irvine, L.M. 2003. ''Seaweeds of the British Isles. Volume 1 Part 3B.'' The Natural History Museum, London. ISBN 1 898298 87 4
* Burrows, E.M. 1991. ''Seaweeds of the British Isles. Volume 2.'' British Museum (Natural History), London. ISBN 0-565-00981-8
* Christensen, T. 1987. ''Seaweeds of the British Isles. Tribophyceae. Volume 4.'' British Museum (Natural History), London. ISBN 0-565-00980-X
* Dixon, P.S. and Irvine, L.M. 1977. ''Seaweeds of the British Isles. Volume 1. Part 1. Introduction, Nemaliales, Gigartinales.'' British Museum (Natural History), London. ISBN 0 565 00781 5
*Greeson, Phillip E. 1982. ''An annotated key to the identification of commonly occurring and dominant genera of Algae observed in the Phytoplankton of the United States'' [Geological Survey Water-Supply Paper 2079]. Washington, D.C.: United States Government Printing Office.
* Irvine, L.M. 1983. ''Seaweeds of the British Isles. Volume 1, Part 2A.'' British Museum (Natural History), London. ISBN 0-565-00871-4
* Irvine, L.M. and Chamberlain, Y.M. 1994. ''Seaweeds of the British Isles. Volume 1 Part 2B.'' The Natural History Museum, London. ISBN 0 11 310016 7
* Fletcher, R.L. 1987. ''Seaweeds of the British Isles. Volume 3 Part 1.'' British Museum (Natural History), London. ISBN 0-565-00992-3
* John, D.M., Whitton, B.A. and Brook, J.A. (Eds.) 2002. ''The Freshwater Algal Flora of the British Isles.'' Cambridge University Press, UK. ISBN 0 521 77051 3
* Stegenga, H., Bolton, J.J. and Anderson, R.J.1997. ''Seaweeds of the South African west coast.'' Boltus Herbarium, University of Cape Town. ISBN 0-7992-1793-x
* Taylor, W.R. 1957. ''Marine algae of the north-eastern coasts of North America.'' Revised edition. University of Michigan Press. Ann Arbor.
===General===
* Chapman, V.J. 1950.p.36. '' Seaweeds and their Uses.'' Methuen & Co. Ltd., London.
* Guiry, M.D. and Blunden, G. (Eds) 1991. ''Seaweed Resources in Europe: Uses and Potential''. John Wiley & Sons. ISBN 0-471-92947-6
* Lembi, C.A. and Waaland, J.R. (Eds.) 1988. ''Algae and Human Affairs''. Cambridge University Press, Cambridge. ISBN 0-521-32115-8
</div>
== External links ==
{{commonscat}}
* [http://www.algaebase.org/ AlgaeBase] - a comprehensive database of over 35,000 Algae (132,000 names), including seaweeds, with over 5000 images and some 40,000 references.
* [http://ucjeps.berkeley.edu/INA.html Index Nominum Algarum]
* [http://en.phyco.org/wiki/Main_Page www.phyco.org]; a wiki-based site that is focused on energy production from algae.
* [http://forums.biodieselnow.com/forum.asp?FORUM_ID=71 biodieselnow.com] biodiesel production-biodiesel from algae
* [http://www.rbgsyd.nsw.gov.au/information_about_plants/botanical_info/australian_freshwater_algae2 Australian freshwater algae] - Sydney Botanic Gardens
* [http://www.algae.info/ Learn about Algae & Algal Blooms] - Rural Chemical Industries (Aust.) Pty Ltd.
* [http://www.whoi.edu/redtide/ Harmful Algal Blooms - "Red tide"] - National Office for Marine Biotoxins and Harmful Algal Blooms, USA.
* [http://www.professorpatents.com/algae.htm Patent Listing]Algae Related United States Patents
* [http://www.nmnh.si.edu/botany/projects/algae/ Algae Section, National Museum of Natural History] - Smithsonian Institution
* [http://www.plantphysiol.org/ www.plantphysiol.org]
* [http://www-cyanosite.bio.purdue.edu/ Cyanosite], a webserver for cyanobacterial research
* [http://www.naturalenviro.com/pondproblems.htm Algae Growth]
* [http://www.swelluk.com/advice/blanketweed.html Blanket Weed]
* [http://www.brphycsoc.org British Phycological Society]
* [http://www.seaweed.ie Seaweed site by Michael Guiry]
* http://www.botanicgardens.ie/educ/vis12.htm
* http://www.ucmp.berkeley.edu/protista/rhodophyta.html - Introduction to Rhodophyta]
* http://www.botany.uwc.ac.za/algae/
* http://www.marlin.ac.uk - Marlin
* http://www.mbari.org/staff/conn/botany/flora/reds.htm - Monterey Bay Flora
* http://www.mbari.org/staff/conn/botany/flora/browns.htm - Monterey Bay Flora
* http://www.mbari.org/staff/conn/botany/flora/green.htm - Monterey Bay Flora
* http://www.time.com/time/magazine/article/0,9171,1616252,00.html
{{-}}
{{Botany}}
{{fisheries and fishing}}
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